This invention relates generally to wire stranding machines, and has particular reference to a novel lock mechanism for positively yet releasably securing a spool of wire in its supporting cradle in a tubular type stranding machine.
Tubular type stranding machines, also known as Larmuth type, have been in use for many years and are well known. In these machines, the strander tube is supported by bearings or rollers and is rotated under power about its longitudinal axis. Within the tube spools of single strand wire are rotatably mounted in cradles and the cradles in turn are supported by bearings at each end, the bearings being coaxial with the tube axis. The cradles are weighted at the bottom and therefore remain stationary when the tube rotates.
The strander tube typically rotates in excess of 2000 R.P.M. and for this reason it is imperative that the individual spools be securely locked in their cradles. A failure that permitted a spool to escape from its cradle and contact the inside of the tube would result in very serious damage to the machine. It will be apparent, therefore, that there exists a need for a positive lock mechanism for securing a spool of wire in its supporting cradle in a wire stranding machine. Because the machine operator must load and unload the spools through openings in the tube side wall, it will be apparent also that a lock mechanism that is easy to operate is also very desirable.
The closest prior art known to the applicant is disclosed in U.S. Pat. No. 407,522, issued July 23, 1889 to M. Furst for a Machine For Making Rope. In this patent, the ends of a spindle carrying a bobbin are held in place by overlying arms that are spring biased into locking position. The springs, however, do not provide a positive lock and it is doubtful if the patented lock mechanism could be relied upon in a machine rotating at the high speeds of present day wire stranding machines.
Other pertinent patents, noted in the course of a preliminary search, are U.S. Pat. Nos. 1,378,932; 1,423,776; 1,495,144; 1,636,466; 2,485,348; 2,567,329 and 4,241,573. The lock mechanisms and devices shown in these patents are for the most part relatively complex.